三维治疗计划系统模拟全身照射的应用研究

The Application Study of the TBI Simulation of Three Dimension Treatment Planning System

目的:采用三维治疗计划系统(3D-TPS)模拟计算全身照射(TBI)的剂量分布。材料和方法:对于全身照射,设置源皮距(SSD)为380 cm,射野大小为40 cm×40 cm,光栏角度为45°,采用自制大水箱测量了直线加速器8 MV光子线水中的百分深度剂量(PDD)和离轴比(OAR)。上述相同照射条件下,在3D-TPS中进行水体模的PDD和OAR的模拟计算并与之测量结果进行对比,确认3D-TPS是否能够模拟计算TBI的剂量分布。采用3D-TPS计算人形体模的TBI剂量分布,采用剂量胶片和热释光测量对计算结果进行了比较和确认。结果:对于水体模中的百分深度量和离轴比,3D-TPS的模拟计算结果与大水箱的测量结果最大误差分别为3%和6%左右。对于人形体模的模拟计算,3D-TPS的模拟计算结果与胶片和热释光的测量结果基本符合。结论:3D-TPS可以较准确地模拟计算全身照射的剂量分布。通过3D-TPS对每个特定病人制作相应补偿块,为更均匀剂量的全身照射治疗提供了可能。

Purpose： Simulating calculation the dose distribution of the total body irradiation （TBI） with three dimension treatment planning system（3D-TPS ）. Materials and Methods： For TBL the source skin distance（SSD） is 380 cm, field size is 40 cm × 40cm, and collimator angle is 45°. The percent dose depth （PDD） and offset axis ratio （OAR） of the linac accelerator is measured with the big water phantom self-made. In the same radiation condition, the PDD and OAR of water which is simulated calculation with the 3D-TPS is compared with the measurement results to confirm whether the 3D-TPS can calculate the TBI dose distribution. The dose distribution of the human phantom is calculated with 3DoTPS, which is compared and confirmed with the film and TLD measurements. Results： The maximum error of PDD and OAR in the water phantom between the measurements and calculations of 3D-TPS are 3% and 6%. The calculation results of the 3D-TPS is according with the measurement results of the film and TLD approximately. Conclusions： 3D-TPS could simulate calculation the dose distribution for TBI accurately. It is possible to improve more uniform dose for TBI with corresponding compensator for specific patient.